A bus company in Illinois is being investigated after sending out an offensive email ad to customers boasting that they “won’t feel like you’re in China when you’re on our buses,” authorities said.

Illinois Attorney General Lisa Madigan issued a subpoena on Monday to Champaign-based Suburban Express, which offers bus services primarily to college students traveling between Chicago and its suburbs. Madigan said she’s seeking documents and records to determine if the company violated the state’s Human Right Act, which bars public accommodations from being denied to people based on their age, race, color, sex, religion, national origin, sexual orientation or gender identity.

“I am concerned that this advertisement may reflect that Suburban Express is discriminating against potential customers,” Madigan said. “Under the law, access to transportation must not be impacted or based on a person’s race or national origin.”

The subpoena follows multiple reports that the company emailed an advertisement to customers on Saturday offering them to buy their tickets early for their treks home in December. According to the email, which was obtained by the Chicago Tribune, “customer-friendly policies” and no fees for baggage were among the reasons why potential customers should pick Suburban.

“Passengers like you,” another perk read. “You won’t feel like you’re in China when you’re on our buses.”

In a message to students, the University of Illinois blasted the ad as “offensive, bigoted, insulting and in direct opposition” to its values.

“The message specifically insulted members of our Chinese, Asian and Asian American communities who are a vital and valued part of every aspect of both the University of Illinois and our local cities,” the statement read. “These types of racist and bigoted statements attacking any members of our community deserve nothing but condemnation from all of us.”

The university does not have a business relationship with Suburban Express, which is not allowed to pick up or drop off passengers at the university, according to the statement.

“We cannot prevent a private company from operating in our community,” the statement continued. “But we can, loudly and unambiguously, say that the opinions expressed by Suburban Express are offensive, bigoted, insulting and in direct opposition to the values of this university.”

Twelve percent of students enrolled at Illinois’ Urbana-Champaign campus this fall are Chinese, according to the Tribune, citing university data.

The company, meanwhile, has apologized on Facebook for the “offensive and inexcusable” remarks in the holiday promotion.

“It was incredibly inappropriate and harmful,” the statement said of the advertisement. “We fully apologize and accept all responsibility for our actions.”

The company’s statement also acknowledged the incorrect perception created by the promotion that Chinese exchange students aren’t welcome to use its buses.

“We are looking forward to working with all students, organizations, and Illinois officials on this matter,” the statement read. “Your responses as a community have inspired us as a company to not only expeditiously make amends, and appropriately apologize without excuse, but to relaunch our company’s conduct completely.”